1. Technical Field
The invention relates to a computer and a control method and, more particularly, to a computer having a power saving state control function and a control method thereof.
2. Related Art
Electricity consuming is one of important factors in designing an electronic product. Manufacturers all wish their electronic products to reduce the power consuming. To a portable electronic device, the less power it consumes, the longer usage time its battery has. A longer usage time of the battery means that a user does not need to often change batteries, and this meets the requirement of the user.
To achieve the power saving effect, a computer system is designed to have a sleeping (power saving) mode. The computer system may enter different sleeping modes according to the user's requirement or the idle time of the computer. Different sleeping modes correspond to different power supply assemblies, respectively, and this may allow certain power supplies to be switched on or off in different sleeping modes. If the computer system works in a normal working mode all the time, all the power supplies are switched on. Thus, the computer system may save much power when it is in the sleeping mode.
When a computer system enters a sleeping mode, if it needs to be switched to another sleeping mode, according to the conventional technique, the computer system needs to be waken up to go back to the working mode first and then enters another sleeping mode.
FIG. 1 is a schematic diagram showing the switching of the conventional sleeping mode. Supposing that the computer system is in the first sleeping mode (S1), if it wants to enter a deeper second sleeping mode (S2) from the first sleeping mode (S1), all the power supplies should be switched on, and the computer should go back to the working mode (S0). Thus, the computer system may enter the second sleeping mode (S2). That is, the computer cannot be switched between different sleeping modes (S1 to S4) directly. No matter which sleeping mode the computer is in, if the sleeping mode needs to be switched, the computer has to go back to the working mode (S0) and then enter another sleeping mode. Thus, the switching time between different sleeping modes is prolonged, and since all the power supplies should be switched on to make the computer go back to the working mode and then perform the following processes (enter another sleeping mode), unnecessary power is consumed.